CLINICAL-FEATURES AND OUTCOME OF CHILDREN WITH FIRST MARROW RELAPSE OF ACUTE LYMPHOBLASTIC-LEUKEMIA EXPRESSING BCR-ABL FUSION TRANSCRIPTS

Although the Philadelphia chromosome (Ph(1)) has been identified as an adverse prognostic factor in acute lymphoblastic leukemia (ALL), litt le is known about the incidence and clinical course of relapsed Ph(1)- positive ALL in children. The incidence was determined by screening of 170 consecutive children with first bone marrow relapse of ALL using the reverse transcriptase-polymerase chain reaction (RT-PCR) and compa rison with cytogenetic analysis. Among these 170 children, 20 (12%) we re found to be BCR-ABL-positive, representing a rate that is about thr ee times higher than that reported for newly diagnosed ALL. Ten of the cases were identified by RT-PCR only. In none of the 21 patients with T-cell immunophenotypes could an expression of the BCR-ABL mRNA be de tected. BCR-ABL positivity was associated with a significantly shorter duration of first remission (P = .0086) and higher white blood cell ( P =.0157) and blast cell counts (P =.0304) at relapse diagnosis. All p atients were treated according to the ALL-REZ BFM 87 and 90 relapse tr ials of the BFM Relapse Study Group. The intensive multiagent chemothe rapy induced a second complete remission in only 60% of children with BCR-ABL-positive ALL compared with in 91% of those without BCR-ABL exp ression (P =.0023). The prognosis of BCR-ABL-positive ALL in children is poor, with a probability of event-free survival at 2 years of 8% ve rsus 50% in those without BCR-ABL expression (P =.0003). Molecular scr eening for the BCR-ABL mRNA or cytogenetic analysis should become part of the routine diagnostic panel for all children with newly diagnosed ALL and is fundamental for children presenting with an early bone mar row relapse. (C) 1996 by The American Society of Hematology.